Refactor music disc commands to use direct give syntax and add custom model data for various shops

assets/minecraft/items/music_disc_13.json

@@ -58,4 +58,4 @@
       }
     ]
   }
-}
+}

assets/minecraft/items/paper.json

@@ -0,0 +1,61 @@
+{
+  "model": {
+    "type": "select",
+    "property": "custom_model_data",
+    "fallback": {
+      "type": "model",
+      "model": "item/generated"
+    },
+    "cases": [
+      {
+        "when": "interior_shop0",
+        "model": {
+          "type": "model",
+          "model": "item/interior_shop0"
+        }
+      },
+      {
+        "when": "pawn_shop1",
+        "model": {
+          "type": "model",
+          "model": "item/pawn_shop1"
+        }
+      },
+      {
+        "when": "food_mart2",
+        "model": {
+          "type": "model",
+          "model": "item/food_mart2"
+        }
+      },
+      {
+        "when": "hat_shop3",
+        "model": {
+          "type": "model",
+          "model": "item/hat_shop3"
+        }
+      },
+      {
+        "when": "clothing_shop4",
+        "model": {
+          "type": "model",
+          "model": "item/clothing_shop4"
+        }
+      },
+      {
+        "when": "jump_up5",
+        "model": {
+          "type": "model",
+          "model": "item/jump_up5"
+        }
+      },
+      {
+        "when": "city_under_siege6",
+        "model": {
+          "type": "model",
+          "model": "item/city_under_siege6"
+        }
+      }
+    ]
+  }
+}

data/new_music/function/custom_items/give.mcfunction

@@ -0,0 +1,4 @@
+# Generic helper for giving custom items with a custom model.
+# Example usage:
+# function new_music:custom_items/give {item:"minecraft:paper", model:"city_under_siege6"}
+give @s $(item)[minecraft:custom_model_data={strings:["$(model)"]}]

data/new_music/function/custom_items/register.mcfunction

@@ -0,0 +1,6 @@
+# Generic registration helper for custom item models.
+# This keeps the item namespace separate from the display model name.
+# Usage: function new_music:custom_items/register {item:"minecraft:paper", model:"city_under_siege6"}
+
+# The resource pack handles the visual model via the shared item selector.
+# This function exists as a general entry point for future custom items.